Day 77: The scorpions of “Evolution Canyon” like it hot

Maybe because I’ve never actually been stung by a scorpion, I think they’re pretty neat beasts. I like their curly, secret-weapon tails and their segmented bodies, and I like my memories of spotting them in my headlamp on a nighttime hike through the Grand Canyon. 

And so, naturally, I was intrigued by a study in which the researchers went looking for scorpions by flipping rocks and shining UV lights — at a place called Evolution Canyon, to boot!

The canyon, in Israel, is a natural laboratory, say Shmuel Raz and colleagues at Israel’s University of Haifa. There, European-like and African-like habitats are separated by no more than about 300 feet (100 meters). 

Scorpions could easily cross the divide to live and hunt throughout — including on the more temperate side. Raz, a doctoral candidate, and his colleagues decided to see whether they do — or whether, instead, they stay true to the hot, dry conditions where they live in most of the world.

Evolution Canyon has steep slopes and runs approximately east-west, which means that the south-facing slope gets up to eight times as much sun as the north-facing slope. Thus, despite identical regional geology and rainfall, one slope, dubbed the African slope, is arid and savanna-like while the other boasts a lush forested environment.

The researchers collected nearly 200 specimens of six different species of scorpions. While four of the species were found on both slopes of the canyon, two were only seen on the more arid, African-like slope.

Furthermore, the European slope of the canyon yielded nearly a third fewer scorpion specimens than the African slope.

Despite the ease of movement between the two canyon walls, the researchers found, the particular adaptations of the scorpions to arid conditions have led to their greater abundance on the south-facing, African slope.

The scientists point out that differences in the diversity of species between Evolution Canyon’s north and south slopes have been observed in other groups of bacteria, fungi, plants and animals. Together, the results show that very localized environmental pressures can mimic climate and terrestrial factors that operate on global scales.

Sources: A Eurekalert press release and the paper, at PLoSONE